FDG-PET/CT Findings of Autoimmune Pancreatitis

Background/Aims: This study aimed to evaluate the clinical utility in Fluorine-18 fluorodeoxyglucose-positron emission tomography (FDG-PET)/computed tomography (CT) in the management of patients with autoimmune pancreatitis (AIP), with special emphasis on differentiating AIP from pancreatic cancer (PC). Methodology: FDG-PET/CT findings of 10 AIP patients were compared with those of 14 PC patients. Results: There were no significant differences between AIP and PC in early and delayed maximum standardized uptake value (SUVmax), and in the ratio of delayed to early SUVmax. Abnormal extrapancreatic FDG uptake was observed in 5 AIP patients, in the hilar lymph nodes (n=4), mediastinal lymph nodes (n=2), abdominal lymph nodes (n=2), and bilateral salivary glands (n=2). After steroid therapy, the abnormal FDG uptake in the pancreas disappeared almost completely in two patients, and the FDG uptake in the hilar, mediastinal and abdominal lymph nodes decreased in one patient. Conclusions: FDG-PET/CT may be helpful to differentiate AIP from PC by assessing FDG-uptake patterns in the pancreas and extrapancreatic lesions, it may have the potential to assess the disease activity of AIP and its extrapancreatic lesions, and it may be useful as a monitoring marker for tapering or stopping steroid therapy.